The invention pertains to a video recorder. In particular, the invention pertains to a video recorder using magnetic tape as the recording medium.
In video recorders of the three systems commonly used at present, i.e., VHS, Video 2000, and Betamax, the chroma signal, after being separated from the demodulated composite color signal, is changed to a carrier signal having a frequency lower than the standard chrominance-subcarrier frequency. The composite video signal is subjected to a frequency modulation, and the sum of the chroma signal of reduced carrier frequency and the frequency-modulated composite video signal is stored on the recording medium by means of a head system. The stored signal is read from the tape by means of the head system during playback, and is then transformed back into the composite color signal.
For the VHS system, the "lower" chrominance-subcarrier frequency is 627 kHz in the case of the PAL standard and 629 kHz in the case of the NTSC standard, the two frequencies being 40.125 and 40 times the horizontal scanning frequencies of PAL and NTSC, respectively. During playback, the coupling of these carrier frequencies with the respective horizontal scanning frequency makes it possible to compensate for variations in tape speed so precisely that in-phase regeneration of the original chrominance subcarrier frequency can be achieved.
Hence it is obvious that, beyond the circuits commonly used in television sets, additional circuits are necessary in video recorders. In conventional video recorders, these additional circuits are implemented predominantly with discrete components and only to a small extent with monolithic integrated circuits performing selected analog-signal-processing functions.